A depth of field as deep as possible is required for an endoscope apparatus (endoscope system) so that the user can easily perform diagnosis and treatment. In recent years, the depth of field of an endoscope apparatus has become shallow along with the use of an image sensor having a large number of pixels, and an endoscope apparatus that performs an autofocus (AF) process has been proposed.
Examples of a known AF control process include the following methods. A first method is used to implement an AF process that is used for a video camera or the like, and performs a focus operation using a change in contrast within an image as a trigger. A second method is disclosed in JP-A-2010-191080. The second method detects a relative change in position with respect to the object and a camera using a motion sensor, and performs a focus operation when the output (e.g., angular acceleration or acceleration) from the motion sensor has become equal to or larger than a predetermined amount.